High temperature coil annealing furnace



Nov. 1, 1960 A, M. 'rol-HR HIGH TEMPERATURE con. ANNEALING EURNACE Filed Dec. s1, 1957 2 Sheets-Shee; 1

BY i i" /ff TTRA/EY Nov. 1, 1960 A. M. Tol-11R HIGH TEMPERATURE conJ ANNEALING EURNACE Filed Dec. s1, 1957 2 Sheets-Sheet 2 INVENTOR. 4A/mamy M. raf/f@ BVM/91% United States Patent O HIGH TEMPERATURE CGIL ANNEALING FURNACE Anthony M. Tohir, Bethel Park, Pa., assignor to United States Steel Corporation, a corporation of New Ilersey Filed Dec. 31, 1957, Ser. No. 706,378

3 Claims. (Cl. 263-36) This invention relates to a high temperature coil annealing furnace and more particularly to such a furnace for annealing silicon steel strip in coils mounted one above the other. In the annealing of silicon steel strip for preferred oriented requirements the steel must be heated to approximately 2025 F. At this temperature the structural strength of the steel is greatly reduced and when annealed with one coil superimposed upon another with a circulating separator therebetween, damage and distortion of the bottom coil results. Prior to my invention high temperature annealing operations were conducted in conventional box type coil annealing furnaces having an inner cover surrounding each coil stack and an outer cover surrounding the inner cover or covers. A separate support for the upper coil fitted within the inner cover. Because of the small space and the fact that the support had to be designed to permit circulation of the protective atmosphere the top coil supporting devices have never been entirely satisfactory.

It is therefore an object of my invention to provide a high temperature cover type coil annealing furnace capable of annealing coils stacked one on top of the other without the use of an independent structure for supporting the top coil.

This and other objects will be more lapparent after referring to the following specification and attached drawings, in which:

Figure 1 is a sectional View through the furnace at one of the coil stacks;

Figure 2 is a sectional View taken on the line II-II of Figure 1; and

Figure 3 is a view taken on the line III-III of Figure 1.

Referring more particularly to the drawings, the reference numeral 2 indicates the supporting structure of the furnace of my invention. Three motors 4 are supported by the structure 2. Each f the motors 4 drives a fan 6. A coil stand 8 of usual construction is mounted on the structure 2 at each motor 4. A hearth plate 10 is mounted on each coil stand 8 with a space 12 therebetween, fan 6 being located in this space. A furnace section 14 having a steel shell 16 and refractory lining 18 is mounted on structure 2. A ledge 20 is provided adjacent the top section 14 for a purpose which will appear later. A channel 22 is fastened to the shell 16 adjacent the top thereof and extends around the periphery of the section 14. An upper furnace section 24 has an angle 26 forming the base thereof with a leg 28 extending downwardly into the channel 22. The angle 26 is attached to a metal shell 30. If desired `an I-beam 32 may be welded to the shell 30 adjacent the bottom thereof with a dependent leg 34 extending downwardly into the channel 22. The shell 30 contains an insulating layer 36 and a refractory lining 38. A refractory arch 40 forms the roof of the furnace. A bracket 41 is attached to the upper part of section 24 in any suitable manner well known in the art. To lift the section 24 a crane hook is inserted into the bracket 41. Electric heating elements 42 are provided on the inside of the sections 14 and 24 providing the necessary heat for the annealing cycle. If desired gas conibustion tubes may be used in place of the heating elements 42. The hearth plate 10 is provided with a counterbored portion 44 for receiving a tubular supporting column 46 having brackets 48 welded thereto intermediate its ends. A grid S0 is supported on the ledge 20. the grid 50 is a rectangular shaped steel plate provided with three circular openings S2 adapted to receive the supporting column 46 and a plurality of openings 54 to permit circulation of the gas.

In operation, a coil C of strip to be annealed is placed on each of the hearth plates 10 and a supporting column 46 inserted through the eye of each coil to rest on the hearth plate l0 in the counter-bored portion 44. The grid plate 50 is then positioned on the ledge 20 with the columns 46 passing through the openings 52. The grid plate 50 also rests on the brackets 48. A coil C is then placed on the grid 50, one around each of the columns 46. The upper section 24 of the furnace is then lowered into place on the lower section 14. The legs 28 and 34 extend downwardly into sand 56 in the channel 22 to form a seal in the usual manner. The protective atmosphere is then delivered into the furnace in the usual manner through a conduit 58 and the motors 4 started in operation. The furnace atmosphere is circulated downwardly through the openings in the supporting columns 46 and radially outwardly through the openings 12. Heat is provided by means of the heating elements 42. After the annealing cycle is completed the coils C are removed by reversing the loading sequence of operations.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

l. A furnace for annealing coils of strip comprising a stationary lower furnace section having a generally horizontal ledge adjacent the top thereof,I a plurality of coil supports in said lower furnace section each adapted to support a lower coil, a supporting column adapted to rest on each of said coil supports and extend through the center opening in said coils, a bracket fastened to each of said columns at substantially the same elevation as said ledge, a coil supporting grid adapted to be supported on said ledge and brackets and adapted to support an upper coil above each lower coil, said grid having openings therein for receiving said supporting columns, a movable upper furnace section adapted to be supported on said lower furnace section, said movable upper furnace section having a refractory lining, and means supported within said furnace sections for heating said strip to a temperature of at least approximately 2000 F.

2. A furnace for annealing coils of strip comprising a stationary lower furnace section having a vertical refractory lining, a generally horizontal ledge adjacent the top of said refractory lining, the inner surface of said refractory lining above said Vledge being at least as far from the center of the furnace as the outer portion of said ledge, a stationary coil support in said lower furnace section adapted to support a first coil, a coil supporting grid adapted to be supported on said ledge and adapted to support a second coil, a movable upper furnace section adapted to be supported on said lower section, said movable upper furnace section having a refractory lining, and means supported within said furnace sections for heating said strip to a temperature of .at least approximately 2000 F.

3. A furnace for `annealing coils of strip according to claim 2 including a supporting column adapted to rest on References Citedin the le of this patent UNITED STATES PATENTS Gjers Jan. 1, 1884 4 Fuchs Jan. 22, 1929 Peterson June 27, 1933 Hardtmayer Mar. 12, 1957 FOREIGN PATENTS France Ian. 4, 1950 

